This invention relates to a menu system used to select one object as an object to be processed from a plurality of objects having a hierarchical structure on a screen of a data processor such as a CAD system for circuit design.
Conventionally, an object-oriented data processor has been developed. A hierarchical menu system is disclosed in patent Application Laying Open Gazette No. 58-195942, in which a menu screen of a lower level is selectable from a menu screen of an upper level, corresponding to a hierarchical structure of objects. Another menu system is proposed in Japanese Patent Application Laying Open Gazette No. 2-240771, in which the hierarchical structure is represented by combining like a tree with lines symbols of objects.
Design for LSI requires a series of procedures from a function design to a layout design. Conventionally, CAD tools are being developed for converting a circuit data (function data) of function level represented per each element by function description language to a circuit data (logic data) of logic level and for converting the logic data to a circuit data (layout data) of mask layout level. For the individual CAD tools, the hierarchical menu systems and the tree-like hierarchical representation suffice, because an individual CAD tool requires only that a plurality of objects of circuit data of the same level is provided, from which it can select and process objects.
A CAD system, called frame work, is developed as a total system of CAD tools for LSI design. In the CAD system of this type, objects having circuit data of various levels such as function data, logic data, or layout data are registered in a library to enable reuse of the design source. The objects have a hierarchical structure corresponding to the hierarchical structure of the circuit elements. When the above-mentioned hierarchical menu system is applied to such a CAD system with objects having such complicated structures, a complex procedure is required for selecting an object to be processed owing to the limited information available from one screen, thus lowering the operationality. When the tree-like hierarchical representation is applied thereto, a problem remains that a user has difficulty understanding the shape, scale, processing state (to what level a data is converted), and location of the elements. These problems exist not only in CAD systems but also in menu systems regarding many objects having complicated structures.